Light film



UNITED STATES ATET OFFICE.

ROBERT JOHN, OF NEW YORK, N. Y., ASSIGNOR, BY MESNE ASSIGNMENTS, TO DAY- LIGHT FILM CORPORATION, A CORPORATION OF NEW YORK,

PHOTOGRAPH POSITIVE AND NEGATIVE.

No Drawing.

To all whom it may concern:

Be it known that I, ROBERT JOHN, a citizen of the United States, and resident of New York, in the county of New York and State of New York, have invented certain new and useful Improvements in Photograph Positives and Negatives, of which the following is a specification.

My invention relates to improvements in photographic positives and n gatives. According to my invention, the negative may be taken in an ordinary camera, using the well known silver salt-gelatin emulsion plate or film, and this negative may be developed in the usual manner.

Instead, however, of printing on sensitized paper directly from this negative, I use it to make a positive plate or film, as in an enlarging camera, except that I preferably expose the positive plate or film through its transparent support rather than in the usual direct method. This plate or film'may also be of the well known silver-salt gelatin type.

According to my invention, I then subject the positive plate or film to certain new processes, which produce an entirely new article, to Wit, a printing plate or film having the image in relief on the surfacecorresponding in gradations and degree to the visibility of the image on the negative. This retained gelatin relief has the capacity to absorb or hold a dye solution, but will readily give up its dye when brought into pressure contact with a suitably coated paper or other carrier. In this Way a number of prints in any desired color may be made.

' The preferred processes for producing my improved photographic plates are based on the fact that certain materials which may be used in the developing solution have a tanning effect on the portions of the gelatin adjacent to the particles of silversalts acted on by the light and converted into metallic silver by the developer, but that this tanning effect may be suppressed or controlled by the use of sodium sulfite or other similar salts. Thus, in the standard developer formulas containing pyrogallic acid, metol, potassium bromid, sodium carbonate, and sodium sulfite, the latter is used in sufficient quantities to entirely prevent this tanning effect, and. when the plate or film is developed, the entire sensitized coating is soluble in Warm Water, both before and after fixing Specification of Letters Patent.

Patented May 23, 1922.

Application filed May 6, 1916. Serial No. 95,957.

in the hypo bath. But if in a developerformula containing I use only from elOto grains of sodium sulfite, the tanning effect may be secured to the desired extent and these portions of the coating rendered insoluble. It is well known that pyrogallic acid is a tanning agent as well as a developing agent and that sodium sulfite is a preservative adapted to prevent oxidation of the pyrogallic acid in solution. It is of course understood by those skilled in the art that when'a thick layer of emulsion is treated, or whenv the exposure is through the transparent carrier, it is advisable, in order to accelerate the action of the pyrogallic'acid, to use large quantities of an accelerator such, for example, as sodium carbonate or its equivalents than when the emulsion layer is thin or exposed on its face. When larger quantities of sodium carbonate thus are used, it is necessary to increase the amount of sodium sulfite. The above sample formula is for treatment of an emulsion exposed through its transparent carrier and therefore contains a comparatively large amount of sodium carbonate with an increased amount of sodium sulfite. In order to obtain the desired printing surface, however, the amount of sodium sulfite in the process disclosed herein is much less than would be used in a developing solution for the usual development of the particular emulsion layer to be treated. The relative proportions of the hardening agent (whether or not accelerated by an accelerating agent) and of the neutralizing agent preferably are such as to control selectively the effective area of influence of the hardening agent.

If then I develop my positive plate or film which has been exposed through the transparent support by subjecting it to a bath of the above specified solution in the usual manner, the image will gradually become visible, and the operator can judge when the plate is properly developed. When the plate has been developed, it may be immersed in a bath of water at a temperature of about 98 F., and in a short time the soluble portions of the emulsion will begin to soften and slide off the plate so that in about five minutes the insoluble gelatin which is adhering to the support, owing to the exposure through the support, will alone remain. lVe will then have the image in relief with the gradations of the relief and the gradations of opaqueness or visibility of the plate corresponding to the light values of the subject photographed. Although the term relief has been used in the broad sense of an absence of flatness, the printing surface obtained by the above process appears to be characterized by great numbers of photographically formed, extremely minute, individual protuberances which are distributed and grouped irregularly so as to represent the photographic lights and shades to be reproduced. Viewed under the microscope it appears as though 'the protuberances were of irregular surface and s arsely scattered in the lights and more dense y grouped in the shades. These protuberances are insoluble in the bath which removes the unafiected gelatin, and are of substantially uniform hardness, the term tanning meaning an affecting of parts of the gelatin so that unaffected parts may be removed. to leave the relief. As the relief is used for printing, it necessarily must be hard enough to withstand use and pressure so that the effect of the tanning may be said to be that of hardening the affected gelatin. The term relief also includes the hardened protuberances surrounded by unremoved gelatin in which case the effect of the tanning also may be said to impart to the protuberanees dif ferent absorption qualities from the remainder of the emulsion as in printing surfaces for ink transfer contact processes.

But there still remains in the gelatin the excess silver bromid or other silver salt used in the emulsion, and also the metallic silver resulting from the developer bath. It is advisable to remove the former by the usual fixing or clearing bath of hypo solution, and it is advisable to remove the latter if the plate is to be used for dye printing, for if the relief is colorless it is easier to tell when all of the dye has. been removed from the relief. The removal of the metallic silver may be accomplished by subjecting the plate or-film to a bath such, for example, as

Water 1 oz. Potassium biehromate 4 grs. Sulphuric acid 12 mms.

' The plate may be kept in this bath until the gradations of color (black. andv white) have disappeared.

It will be obvious that the order in which *the plate is subjected to the hot water bath,

the fixing bath and the bleaching bath is speaking, any wool dye may be used, and

some of the cotton dyes would give satisfactory results. Whether the relief actually absorbs the dye to any considerable extent or only carries it on its surface has not been determined. Whatever the action, the protuberances of the relief afford a dye carrying surface greatly in excess of the flat surface to 'which they are affixed, This gives a rapidity of action never heretofore attained, the taking up and transfer of the dye to and from the protuberance being practically instantaneous. This results in a finished reproduction in which the diffusion of dye or color is imperceptible when the picture is enlarged twenty-five diameters which is much less than the usual enlarg'ement in commercial motion picture projection.

In a dye solution containing approximately 32 ozs. of water and 34 mms. of acetic acid, I use approximately 4 grs. of tartrazine for a yellow picture, 5 grs. of crystal ponceau or zylene red for a red picture, and approximately 8 grs. of patent blue for a blue picture. these or other dyes in proper proportions other colors may be secured. The term color is meant to include black, which sometimes is referred to technically as an By comblnmg bath and the excess dye removed in any desired manner from the face of the plate as by a squeegee, or rubber rollers,

The plate is then brought into contact 1 with paper or other support coated with a colloid or other substance having an affinity for the dye used. I find that threeper cent of gelatin in water forms a suitable coating.

If new the coated paper and the dyed print plate arebrought into'pressure contact, as by passing them between more or less resilient rollers, the dye will leave the relief and adhere to the coating on the paper. In this way the image is reproduced on the paper in any desired color. Praetically any number of prints may be made in this manner. After each application of the printing plate all of the dye contained may be removed, leaving the original colorless relief.

By making color separations through color screens in accordance with known principles, a plurality of positive relief print plates can be obtained to be used with different dyes, and by printing all of these on the same surface in well known manner, a photographic reproduction in natural colors can be produced. Also by exposing the positive plate direct instead of through the transparent support I can strip the coating off the support, preferably after the plate has been developed, and apply it to a copper or other plate to be etched. After the soluble portions of the gelatin have been washed out with warm water, as already described, the relief may be used as an acid resist in etching the plate. For certain forms of photogravure this may be done with the negative plate instead of the positive plate.

Many modifications of my invention will be apparent to those skilled in the art without departing therefrom or from the scope of the claims, my invention not being limited to the embodiments thereof chosen for purposes of illustration but consisting of a contact transfer surface capable of acquiring and giving up a desired color with great rapidity.

Having described my invention, what I claim is:

1. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances which are distributed and grouped irregularly so as to represent photographic lights and shades.

2. As an article of manufacture, abase having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances which are distributed and grouped irregularly so as to reproduce photographic lights by sparsely scattered protuberances and photographic shades by densely grouped protuberances.

3. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances insoluble in water which are distributed and grouped irregularly so as to represent photographic lights and shades.

4. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances capable of taking up and delivering a liquid dye which are distributed and grouped irregularly so as to represent photographiclights and shades.

5. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances of gelatinous composition which are distributed and grouped irregularly so as to represent photographic lights and shades.

6. As an article of manufacture, a base having on its surface great numbers of nat urally photograph ically formed, extremely minute, individual protuberances of substantially uniform hardness which are distributed and grouped irregularly so as to represent photographic lights and shades.

7. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances having irregular surfaces which are distributed and grouped irregularly so as to represent photographic lights and shades.

8. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual. protuberances aflixed to the base which are distributed and grouped irregularly so as to represent photographic lights and shades.

9. As an article of manufacture, a base having on its surface great numbers of naturally photographically formed, extremely minute, individual protuberances which are distributed and grouped irregularly so as to represent photographic lights and shades and providing a surface which owing to its irregularities is greatly in excess of the flat surface on which it is mounted.

10. As an article of manufacture, a base having on its surface naturally photographically formed protuberances distributed and grouped to represent photographic lights and shades and spaced apart so that the base even in dense shadows is not covered entirely.

11. As an article of manufacture, a base having on its surface naturally photographically formed protuberances distributed and grouped and not entirely covering the base.

12. As an article of manufacture, a base having on its surface naturally photographically formed individual protuberances each of which is separated from adjacent protuberances in at least one place.

13. A silver salt emulsion plate which has thereon adjacent the surface of the plate hardened protuberances of gelatin with the surface of the plate exposed between said protuberances.

14:. A silver salt emulsion plate in which the particles of silver are surrounded by insoluble gelatin which in turn are surrounded by soluble gelatin.

15. As an article of manufacture, base having on its surface an emulsion containing therein great numbers of naturally photographically formed. extremely minute, individual particles of different absorption qualities from the remainder of the emulsion and which are distributed and grouped irregularly so as to represent photographic lights and shades.

Signed at New York in the county of New York, and State of New York this fourth 

